Check Engine light

Discussion in 'Gen 2 Prius Technical Discussion' started by swede70, Jun 30, 2016.

  1. swede70

    swede70 Junior Member

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    we have a Prius from 2004.
    We have had problems with the starter battery. This is because the car is so rarely droven. So to fix this I have charged the battery several times. But have not disconnected the battery cables before. I don´t know if thats the reason why we have problems though. But you can suspect that..
    One morning when we should drive the car we saw that the "check engine light" came up on the dashboard. And other warnings also.
    I bought an OBD scanner and hooked it up. P3030..
    So I took the hybrid battery out of the car and cleaned all poles and connections. I measured each battery cell to approx 7,6 V.
    I also bought a new starter battery.
    Now, I have put all toghether again. But P3030 is still the case.

    Is it possible to measure the voltages from the busbar module by measure on the contact to the ECU? I have tried that but don't get stable results. The voltages goes up and down all time..
    My last hope is that a wire between battery busbar and ECU is broken. But I couldn't reqognize that when I had the battery out of the car.

    Are there any other stuff that would be worth checking?

    //swede70
     

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  2. swede70

    swede70 Junior Member

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    Thanks,
    I have now measured the resistance between each connector and battery busbar according to the manual. But found no open circuits.
    What can I do now?
     
  3. Patrick Wong

    Patrick Wong DIY Enthusiast

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    The issue is the battery ECU is reporting a fault because at least one of the voltage sense wires is having a problem. You have said that your ohmmeter tests do not point out a problem. Hence, either there is a problem with the way you are doing your test, or the battery ECU itself is failing.

    If you think that there may be a problem with your testing technique, then I suggest you buy a new busbar assembly that has new voltage sense wires, and install that.

    If you believe there is no problem with your testing and inspection technique, then you may need to replace the traction battery ECU with a used unit. For example,
    2004 09 Toyota Prius HV Battery ECU and Related Parts | eBay
     
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  4. swede70

    swede70 Junior Member

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    Ok, I've ordered an used unit now. We will see what happens in a couple of days..
     
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  5. swede70

    swede70 Junior Member

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    That worked fine!!
    Thank you so much.
     
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